Graphics

  Each user has a graphics (or overlay) channel associated with the image display. The currently available commands associated with the use of the overlay channel are listed below:

SET/OVERLAY - enable the overlay of graphics on top of the image
CLEAR/OVERLAY - disable the overlay memory
LOAD/OVERLAY - load a LUT for the graphic channel (for experts only!!)
SCROLL/OVERLAY - scroll the graphics channel with the image channel
ZOOM/OVERLAY - zoom the overlay with the image channel
DRAW/... - draw a geometric shape like CIRCLE, RECTANGLE, etc. in the overlay plane
SET/CHANNEL - designate a channel as image or graphics

Turning off the overlay/graphics via CLEAR/OVERLAY only disables the overlaying of the graphics. To really get rid of what is in the overlay channel you must use CLEAR/CHANNEL OVERLAY.
Furthermore, due to the internal hardware of the IP8500, disabling the overlay will also turn off the visibility of the cursors!